Contamination of groundwater with chlorinated solvents, such as tetrachloroethene
(PCE) and trichloroethene (TCE), is a serious problem at many sites within
the United States. One such site is Aberdeen Proving Grounds. Discharges from
several sources has led to extensive contamination of groundwater with a mixture
of chlorinated organic pollutants. This is of concern because of the toxicity
of the chlorinated pollutants to aquatic organisms. Natural attenuation is
an inadequate treatment technology at these locations and engineered bioremediation
approaches are needed to supplement naturally occurring processes at these
locations. The effect of bioaugmentation at a single seep that is contaminated
with tetrachloroethane (TeCA) and TCE within the West Branch freshwater wetland
area will be evaluated. Two sets of replicate microcosms will be constructed
using serum bottles and anaerobic sediment and groundwater collected. The
evaluations will be performed in the laboratory using anaerobic batch microcosms
containing sediment and groundwater collected from a seep. The effect of bioaugmenting
the seep with an enrichment culture will be evaluated by monitoring the concentrations
of the parent and daughter compounds over time. The effect of the added enrichment
culture on the structure of the seep bacterial community and its ability to
survive in the seep system will be evaluated using a DNA fingerprinting technique,
known as terminal-restriction fragment length polymorphism (T-RFLP). In T-RFLP,
unique bacterial populations are distinguished based on differences in their
16S rDNA sequences. Thus, the loss of enrichment of specific populations following
bioaugmentation should be evident in T-RFLP fingerprints of the total bacterial
community.